Service observing system for telephone exchanges



H. E. PHELPS SERVICE OBSERVING SYSTEM FOR TELEPHONE EXCHANGES Filed Oct. 10, 1933 5 Sheets-Sheet l /fv VEN Tof;a H E PHE LPS ATTORNEY H. E. PHELPS April 2, 193s.

SERVICE OBSERVING SYSTEM FOR TELEPHONE EXCHANGES Filed Oct. 10, 1933 5 Sheets-Sheet 2 nv VENTO@ HE PHELPS er QUIK D OL.

SERVICE OBSERVING SYSTEM FOR TELEPHONE EXCHANGES Filed Oct. l0, 1933 5 Sheets-Sheet 3 6 ATTORNEY H. E. PHELPS Apri 2, 1935.

SERVICE OBSERVING SYSTEM FOR TELEPHONE EXCHANGES 5 Sheets-Sheet 4 Filed Oct. l0, 1953 Wm TL mw WP Fm H.

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Il VI hk` u 0 .n h bwl@ v o ATTORNEY April 2, 1935. E, PHELPS 1,996,213

SERVICE OBSERVING SYSTEM FOR TELEPHONE EXCHANGES Filed Oct. 10, 1933 5 Sheets-Sheet 5 T0 OTHER T0 Uff/ER 70071959 i VK QSERVERS POS/T/ONS. C/RCbr l 5 /Nl/E/v TOP H. E. PHE L PS Patented Apr. 2, 1935 1,996,213

UNITED STATES PATENT OFFICE SERVICE OBSERVING SYSTEM FOR TELEPHONE EXCHANGES Henry Edison Phelps, Tuckahoe, N. Y., assigner to American Telephone and Telegraph Company, a corporation of New York Application October 10, 1933, Serial No. 693,009 20 Claims. (Cl. 179-1752) This invention relates to telephone exchange even though the circuit between these two lines systems and more particularly to such a system may be broken within the cord circuit. providing means whereby an observer at a cen- A full understanding of the operation of the tral point may determine the character of service system contemplated by the invention as well as being rendered by the telephone operators in esan appreciation of the various features may be 5 tablishing connections between subscribers. gained from a consideration of the following de- This type of central office system, which is comtailed description read in connection with the monly referred to as a service observing system, annexed drawings in which: is usually provided in order that the operating Figure 1 shows a service observers telephone V supervisors may collect data concerning, for exset and a portion of the associated circuits in- 10 ample, the quality of service the subscribers are dividual to a service observing position; receiving in general, or the time elements of the Fig. 2 shows a monitoring jack at the service service as an aid in determining the circuit and observing position for monitoring on an operapparatus requirements in various parts of the ators telephone circuit and a service observing system, and also that they may have a means link circuit for connecting the observers equip- 15 for detecting particular irregularities which may ment to any cord circuit which the operator may have been complained of by certain subscribers. elect to utilize in setting up a connection;

In order that complete data may be obtained a Fig. 3 shows a portion of two telephone lines, system of this nature should provide means, unan operators cord circuit used in establishing a der control of the observer, whereby progress of connection between such lines and the operators 20 a call from its initiation to its completion may telephone circuit associated therewith. While the be followed and whereby all signals, circuit concircuit here shown is of the type used to provide ditions and ope-rations performed in buildingtoll or long distance connections, the invention is up the circuit, maintaining conversational conapplicable also in the instance of cord circuits of' nection and iinally "breaking-down the connecother types; 25 tion may be observed. For econo-mic reasons itis, Fig. 4 and Fig. 5 show modifications of the link of course, desirable that duplication for the circuit shown in Fig. 2; and specific purpose of providing service observing Fig. 6 shows the arrangement of the above figfacilities of the apparatus necessary for the usual ures in illustrating the system contemplated by steps of completing and supervising the telephone the invention (Figs. 2, 4 and 5 are interchange- 30 connections, be so far as possible avoided. able).

An object of the invention, therefore, is to Referring now to the drawings let us assume, reduce the amount of terminal equipment used at for purposes of description, that the service oba service observing position. server at observing position No. 3, shown in Fig.

Another object is to provide automatic means 1, desires to determine the quality of service being 35 under control of an observer for making connecrendered by the operator at switchboard position with any busy telephone channel for purtion No. 4, shown in Fig. 3. Assuming that the poses of observation. link circuit provided is of the type shown in Fig. 2,

Still another object is to provide means wherethe service observer will insert her plug |0| in by the condition of the supervisory signals at the jack 20| which is provided at her observing desk 40 operators position may be indicated at the servand which is individual to operators position No. ice observing position. 4. The right hand receiver |02 of the observers According to a feature of the invention means set is thereby connected through amplier |05, are provided whereby the observers equipment conductors |03, break contacts of key |06, conmay be connected to a cord circuit being used by ductors |04, plug |0I, jack 20|, conductors 302 to 45 a telephone operator in completing a connection. the operators telephone set 30| at switchboard According to another feature means are inposition No. 4. eluded whereby the condition of the supervisory Let it be assumed now that the operator receives signals at the operators position may be oba call over line conductors 303 and that she elects served at the service observing position. to use her fth cord (which we shall assume is 50 According to another feature means are prothe one shown in Fig. 3) in answering the call. vided whereby the service observing equipment She will therefore insert plug 304 in jack 322. She may be connected to both ends of the operators next operates key 305 which connects her telecord circuit whereupon observations may be phone set 30| to the cord circuit and also conmaintained on both the calling and called lines nects ground 354 through the lower make contact 55 of the key to conductor 305 which is individual to the fifth cord.

The service observer will, at this point operate her key IilB which disconnects receiver I02 from the monitoring connection previously traced and connects it, through make contacts oi key |06, to conductors I0'I and thence to the two outer upper make contacts of relay ZIZ. Operation of key ISS also completes a circuit from battery |82, lower make contact of key |36, sleeve of plug IOI and jack 20I, conductor 202, winding of relay 203 to ground 353, relay 203 operating over this circuit.

The operation of relay 203`completes a circuit traced from battery 2 i4, lamp 203, conductor 205, middle upper make Contact of relay 293, conductor 305, lower make contact of key 335 to ground 354, lamp 2&4 being energized over this circuit. Lamp 204 is located at the service observers position and is individual to the fifth cord at whichever switchboard position the service observer is in connection with at the time. The lamp thus, by lighting, indicates to the observer that the operator has elected to use her fifth cord circuit. The other make contacts of relay 203, except the lower outer, are associated with other cords at the switchboard position and with other indicator lamps at the observers position.

In order to follow the progress of the call iurther the observer now momentarily operates key 206 which is located at the observers position and which is individual to the fifth cord circuit at switchboard position No. 4. (Lamp 206 by lighting has, as described above, indicated that the fth cord circuit is being used by the operator.) Operation of key 203 completes a circuit traced from battery 2IE, winding of relay 20'5, conductor 25B, upper make contact of key 236, break contact of key 209, conductor 2I0, lower outer contact of relay 253 to ground 2I5, relay 201 operating over this circuit. Relay 201 is slow-to-release and remains operated while key 236 is restoring to normal whereupon a locking circuit for the relay is established, traced from battery 2I6, winding of relay 231, left make contact of relay 201, conductor 2! I, break contacts of key 250 and key 205, break contact of key 209, conductor 2I0, lzower outer make contact of relay 203 to ground As relay 201 operates a circuit is completed from battery 2I8, winding of relay 2 I2, right make contact of relay 251 to ground 2II, relay 2I2 operating over this circuit.

Relay 2I2, by operating, connects: (l) conductors IGT to monitoring conductors 331 (through the two outer upper make contacts of relay 2 I2) which are connected to the talking conductors at plug 3M the answering end of the cord circuit, (2) conductors |08 to monitoring conductors 308 (through two inner lower make contacts of relay 2 I2) which are connected to the talking conductors at plug 3M the calling end of the cord circuit (3) conductor I09 to conductor 309 (inner upper make contact of relay 2I2) which is connected to the sleeve circuit at the answering end of the cord circuit, and (4) conductor I!!! to conductor 3I0, (outer lower make contact of relay 2 I2) which is connected to the sleeve circuit at the calling end of the cord circuit.

Right hand receiver |32 of the observers telephone set is now connected for monitoring on the answering end of the cord circuit over conductors |01 and conductors 301 while left hand receiver III is connected for monitoring on the calling end of the cord circuit over conductors IDS and conductors 308. Amplifiers I05 and II2 are shown associated with these respective circuits but need not be included if not required or may be supplanted by other forms of repeating apparatus.

Marginal relay I I3 is connected in parallel with the answering supervisory lamp 3I3 .over conductors |09 and 309,while marginal relayV II4 is connected in parallel with calling supervisory lamp 3I'I over conductors IIO and 3I0. These relays through their operation, which is controlled in a manner now to be described, control the energization respectively of lamps II5 and IIS.

As shown telephone line 303 is provided with a supervisoryrelay 3I I which controls the resistance of the: line sleeve circuit. When the relay is in operated condition, due to the presence of a talking connection at the other end of the line, the sleeve circuit will present a high resistance path to ground 320 through resistance 319. When the relay is in released condition, however, due to the breaking down offthe talking connection at the other end of lesser resistance to ground 320 is provided through the break contact of the relayv and resistance 3 I2;

The resistances of! these respective paths are-of` such a value that when plug- 304-isfinserted in jack 322, the current through lamp 3I3, sleeve of 322, resistance 3I0 cient to light lamp 32I but, if-the path `Iso/ground be completed through-resistance 3I2insteadof through resistance SIB, the current flow wi1lbe sufiicient to cause lamp therefore that, when the cord circuit is connected to line 303, answering supervisory lamp 3I3vwill remain dark present on a held line but willbe lighted onthe low resistance sleeve circuit present when the line is released. Now marginal relay II3"atthe service observing position operates in amanner similar to lamp 3I3 just described; i; e., whenfthe operating circuit is completed from battery 323 through the winding of'relay H3, conductor? |53', inner upper make contact otrelay 242; conductor 399, sleeve of plug 304 and jack 322 and through resistance 3I9'to ground-323', the current iiow is not suflicient to cause operation of relay` 323, but when the path to ground is completed through break contact of relay- 3| Iiand resistance 3I'2'instead of through-resistance 3I3; the current flow is sufficient that the relay operates. Operation of relay I'I3-'in turn completes a circuit'for energization of lamp II5, traced from battery 325:, lamp I I5, make contact of-relay I |31 to ground 324. Therefore as relay I I3Loperates in step with lamp 3I3 and as it controls by its operation the energization of lamp I I5 at the service observing position, the observer, by noting the condition of lamp II5, may ascertain the condition of. answering supervisory lamp 3I3 at the switchboard position. In a like manner lamp Iliat the service observing position indicates the condition oiy calling supervisory lamp 3I1`.

The switchboardl operator, having nsertmi answering plug 354 in jack 322'and having operated key 305-as mentioned above, now converses with the calling party andobtainswhatever information is needed'to complete the call. The observer, through the monitoring connections to the answering and callingcords traced above, isenabled to listen to the conversation betweenv the operator and the calling party.

Assuming that theoperator finds that the calling subscriber desires a connection with line 3I 5;

plug 30! and jack the line a shunt path ofla:

flowing from battery 32| to groundf325x will not be sui- 3 I 3|to light It is-evidenti onthe high resistance sleeve circuit she will insert plug 3| 4 in jack 326. Now line 3 I5 has a circuit similar to that of line 303 and as the line is open at its distant end a low resistance sleeve circuit will be presented and calling supervisory lamp 3|1 will light. (As pointed out above the operation of lamp 3| 1 is similar to that of lamp 3 I 3 which has been explained.) The lighted condition of lamp 3|1 is indicated to the observer as relay I i4 and lamp I I6 at the service observing position operate, as pointed out above, in step with lamp 3 I 1.

The operator having inserted calling plug 3|4 in the jack of the desired line operates her ringing key 3|6 which places ringing potential across the tip and ring conductors of the desired line, thereby causing operation of the signaling relay in the line. As monitoring conductors 308 are also connected across the tip and ring of the calling cord, connection of ringing potential to the tip and ring by operation of key 3|6 is repeated through conductors 308, conductors |08 and through amplier ||2 to receiver III, this connection causing a click in the receiver and indicating to the observer that ringing potential has been applied to the called line. A second click, caused by release of key 3|6, indicates to the observer the removal of ringing potential.

Now when the called party responds, calling supervisory lamp 3|1 is extinguished due to the increased resistance of the sleeve circuit and lamp I I6 at the service observing position is likewise extinguished indicating to the observer the response of the called party.

The observer is now enabled to listen to the conversation of the calling and called parties and to observe the condition of the various supervisory signals. As receiver |02 is connected to the answering end of the cord and receiver I to the calling end; the observer will be able to monitor on each line even though the operator may operate one of the cord splitting keys such as 3I8 in order to converse with one of the parties to the exclusion of the other. Should the operator disconnect one or both ends of the cord circuit from the connected lines in order to connect them with other lines, the observer will remain connected to the same cord for observation thereon.

After the parties have been connected and the conversation has been started, the operator will ordinarily release her key 305 thereby disconnecting her telephone set from the cord circuit. Release of key 305 removes ground 354 (lower make contact of key) from conductors 306 and 205 thereby interrupting the energizing circuit of lamp 204. The lamp is therefore extinguished indicating to the observer that the operator has disconnected her telephone set from the cord circuit.

Now when the observer wishes to disconnect from the cord circuit, either before or after the termination of the conversation she releases key |06. Release of key |06 returns receiver |02 to a monitoring connection on the operators telephone set (through plug |0I, jack 20| and conductors 302) and removes battery |82 from the sleeve of plug |0| thereby interrupting the operating path of relay 203 which releases. Release of relay 203 in turn removes ground 2|5 (lower outer make contact of relay 203) from conductor 2| 0 thereby interrupting the holding circuit of relay 201 which thereupon restores to normal. Release of relay 201 in turn removes ground 2| 1 from the operating circuit of relay 2|2 which thereupon restores to normal thereby opening the monitoring and supervisory connections between the two ends of the cord circuit and the observer. The observer may now withdraw her plug from monitoring jack 20| or may, by again following a procedure similar to that outlined above, observe on other cords of the same operators position.

It will be apparent from the above that the observer has been enabled to follow the progress of the call from its initiation to its completion, to observe the operation of the various supervisory signals, to monitor on the conversations of the subscribers and that of the operator, in short, to obtain complete information relative to the service rendered.

Let it now be assumed that the circuits of Fig. l and Fig. 3 are connected through a link circuit of the type shown in Fig. 4 instead of through the circuit of Fig. 2. The arrangement shown in Fig. 4 may be used when it is desired to follow the operations of the switchboard operator from one cord to another as she shifts her own connections from cord to cord. The circuit of Fig. 4 operates in conjunction with the circuits of Fig. 1 and Fig. 3, the operation of which circuits have been described in detail above.

Assuming now that the observer inserts her plug |0| in jack 40| and operates her key |06, battery |82 is thereby connected through the lower make contact of key |06, sleeve of plug |0| and jack 40|, winding of relay 403 to ground 406, relay 403 operating over this circuit. Operation of relay 403 connects a plurality of relays, such as 4|?, each oi which is individual to a cord circuit at switchboard position No. 4, to the conductors leading to contacts of the respective cord circuit talk keys. In the instance of relay 4|2, illustrated, the connection is through conductor 306 which leads to key 305.

Assuming again now, as we did when describing the previous system including Fig. 2, that the switchboard operator elects to utilize her fifth cord in answering a call, she will operate talk key 305 thereby connecting ground 354 to conductor 306. This completes the operating circuit of 4|2 which, when operated, connects the monitoring and supervisory conductors of the observing position to the calling and answering ends of the fth cord, in a manner similar to that described above in connection with the operation of relay 2 |2.

Now should the operator release key 305 and operate a similar key in one of her other cord circuits, ground 354 will be removed from conductor 306, thus interrupting the operating c1rcuit of relay 4| 2 which releases and opens the observing connections to the fth cord while the operating circuit of a relay similar to 4|2, but associated with the other key operated, will be completed, thus connecting the observer to the next cord. That is, each time one key, such as 305, is released and another operated, an associated relay, such as 4|2, is at the same time operated thus keeping the monitoring and supervisory conductors of the observers position in connection with the particular cord being used by the operator.

The circuits of Figs. l and 3 may also be connected by the type of link circuit shown in Fig. 5. This type of link circuit may serve a plurality of switchboard positions, two positions being served by the circuit illustrated. Jack 50| is associated with position #4 while jack 560 might, for example, be associated with position #5. The complete circuit associated With jack 560 is not illustrated in detail, as it is similar to that associated with jack Sill which is shown, but it might be here pointed out that each jack has associated with it relays, (in the instance of jack 50 I, relays 553 and 51|! and in the instance of jack 560, relay 552 and a relay similar to 5H), not shown) which. serve to direct the link, when seized, to the proper position. Lamps, such as 5|! and 55|, are associated with each jack to indicate when a common link is in use. These lamps are connected in multiple so that they are energized simultaneously. A group lamp, common to all the positions served by the one link circuit may of course, be utilized if desirable rather than a lamp individual to each position. The link circuit is provided at each end with a selector, selector 552 `serving to find or select the conductors leading to the proper observers position and selector 5|2 serving to rind or select the conductors leading to the proper cord circuit. The wiring of the selectors has not been completely shown, in the instance of selector 552', only the wiring of the fourth contacts of each arc, which are associated with observers position #3, being completely shown and in the instance of selector 5 I 2, only the wiring associated with cord #5 being completely shown.

Referring now to the system of Figs. l, 5 and 3, let assume, as before, that the observer inserts her plug EOI in jack 50| thereby connecting right-hand receiver ||l2 over conductors |04 and 3532 for monitoring on operators telephone set 35i. he observer now operates key |55 which completes a circuit from receiver |02, amplifier |55, conductors |53, outer upper and inner lower make contacts of key |55, conductors |51 to the fourth contacts of the seventh and eighth arcs ci selector 552. Operation of the key also connects battery |82 through the sleeve of plug |0| and jack winding of relay 553, upper break contact of relay break contact of relay 555 to ground 551i, relay 553 operating over this circuit.

Operation of relay 553 (l) removes ground 565 from the fourth contact of arc #l of selector 532 (previously supplied through lower break Contact of relay 553) and connects ground 501 to the fourth contact of arc #f2 of the selector (lower inner make contact Of relay 553), (2) removes ground 555 from its own operating circuit and substitutes a holding ground 55"' (inner upper make Contact of relay 553), (3) completes a circuit from battery 555, winding of relay 505, upper outer make contact of relay 553 to ground 551, relay 555 operating over this circuit, and (a) completes a circuit from battery 559, winding of relay lower outer make Contact of relay 593 to ground relay 5|0 operating over this circuit.

The operation of relay 555 completes a circuit from battery 5i2, lamp 5H, lower outer make Contact ci relay 535 to ground 554, as well as a circuit from battery 555, lamp 55|, lower outer make contact of relay 555 to ground 555, lamps Eli and 552 being lighted over this circuit to indicate to other observers that the common link circuit is in use.

Noir, assuming that the operator has operated her talk key 355, a circuit is completed from battery il, winding of relay 5M, upper inner make contact of relay 5H), upper inner break contact of relay 5|5, lower outer make contact of relay 51E), conductor 355 to ground 354, relay 554 operating over this circuit. Ground 354 is also applied, through conductor 306 and lower outerlmakezcontact of relay 51|), to the-rsticon tact of arc #I of selector 5|3 thereby completing: a circuit through brush 5|5, break contact and winding of stepping magnet 5|9 to battery 52B, this circuit being effective to start selector 512. By the operation of is also applied througlzi conductor 305 and middle upper make contact of relay 5M to the sixth contact of arc #2 of selector SI2.

Selector 5|2 having been started, as previously mentioned, continues its stepping action by virtuecf an. operating circuit traced from battery 525, winding of stepping magnet 5|9, break contact vof stepping magnet 519, brush 5I5 and contacts of arc #I of selector 5|2, upper outer break contact of relay 5|5 and upper break contact of relay 522 to ground 52|. This stepping action continues until the sixth contacts of the arcs are reached whereupon a circuit is completed from battery 523, windingv of relay 522, brush 5|1, sixth contact ofV arc"#2 of selector 5|2, middle upper make contact of relay 5M, conductor 355, lower make contact of key relay 522 operating over this circuit.

The operation of relay 522 per break contact, the operating circuit traced above by which the stepping magnet 519 of se lector 5|2 was energized and the selector therefore stops with its brushes, 515, 5|? and 518 in engagement with the sixth contacts of arcs #L #2 and #3 respectively. The operation of relay 522 also completes a circuit traced from battery 524, winding of relay 5i5, upper make contact of relay 522 to ground 52|, relay 5|5 operating over this circuit.

Relay 5|5, upon operating, locks up on a circuit controlled by relay 505, trac-ed from battery 521i, winding of relay 5l5, lower inner make contact of relay 5I5, upper inner make Contact of relay 555 to ground 525 and, by its operation, (l) completes a path from battery 521, winding of stepping magnet 528, break contact of stepping magnet 528, brush 525 and first contact of arc #l of selector 552, lower outer make contact of relay 5|5 to ground 526, stepping magnet 528 being energized over this path to start the brushes of selector 552, and (2) interrupts, at its upper inner break contact, the energizing path of relay 5|4 which thereupon releases.

Release of relay 5M interrupts, at its middle upper make contact, the energizing circuit of relay 522 which thereupon releases. The release of relay 522 does not again start selector SI2 (energizing circuit thereof previously completed through break contact of relay 522 when in released condition) however, as the energizing circuit of stepping magnet 5I9 has been previously interrupted by operation of relay 5%5.

The stepping action of magnet 528 having been started, as stated, above, continues as ground is applied to each Contact of arc #I from relays (similar to 553) associate-fi therewith, until the brushes reach the fourth contacts of the arcs when the energizing circuit is interrupted, relay 553 being in operated condition thereby removing ground 525 from the fourth contact of arc irl, and the selector brushes stop.

Now with the brushes of selector 592 in contact the fourth contacts of the associated arcs and with the brushes of selector 5I2 in contact with the sixth contacts of the associated arcs, a circuit is completed to operate relay 530, traced from battery 559, upper outer make contact of relay 5H); winding of relay 530, sixth contact of arc#3 ofselector 5I2,A brush relay 5|4, ground 354iy 395 to ground 354,

interrupts, at its up- 5|8,1lower middle' make contact of relay 5I5, upper outer make con. tact of relay 505, brush 530 and fourth contact of arc #2 of selector 502, lower inner make contact of relay 503 to ground 501, relay 530 operating.

As previously pointed out monitoring conductor pairs w1 and IIIB are connected to the fourth contacts of arcs #1 and #8 and arcs #4 and #5 respectively ci selector' 502 and operation of relay 530 connects these conductors, through its two outer upper and its two inner lower make contacts, to conductor pairs 301 and 300 respectively and through these last mentioned conductors to the answering and calling ends of the cord circuit. In the same manner supervisory conductors I09 and H0 are connected through conductors 309 and 3 I 0 to the sleeve circuits of the answering and calling cords.

As in the instances of the two systems previously described, the observer through conductors 301 and 308 is now enabled to monitor on the conversations of the two subscribers as well as that of the operator and is, by operation of lamps IIS and H5, appraised of the conditions of the supervisory signals 313 and 3I1. In fact the functioning of the system, in general, is similar to that described above, the type of connecting link circuit alone being different.

Assuming now that the observer, having finished her check, removes her plug IOI from jack 50i (or restores key |06 to normal position), the energizing circuit of relay 503 is interrupted by removal of battery I82 and the relay therefore restores to normal. The release of relay 503, (1) places ground 506 on the fourth contact of arc #I of selector 502 thus completing an energizing circuit for stepping magnet 528 and starting the brushes which continue to rotate until they reach normal position or until another ungrounded contact is found on arc #L (2) interrupts the operating path of relay 5I0 by removal of ground 501, relay 5I0 thereby restoring to normal and (3) interrupts the energizing path of relay 505 by removal of ground 501, relay 505 thereupon restoring to normal.

Release of relay 5I0 interrupts the operating path of relay 530 by removal of battery 509, relay 530 thereupon restoring to normal, While the release of relay 505, by removing ground 525 from the holding path of relay 5I5, causes its release. Release of relay 5I5 extends the operating path of selector magnet 5I0 through its (relay SI5) upper outer break contact to the break contact of relay 522 and thereby to. ground 52|, the stepping magnet being energized over this circuit to rotate the selector brushes to normal position.

'Ihe circuits now having been restored to normal condition may be utilized for the next observation.

While certain specific embodiments of the invention have been selected for illustration and description, it is not intended to indicate that the invention is so limited. It is, in fact, intended to indicate the limitations of the invention only by the attached claims.

What is claimed is:

1. In a service observing system, a busy telephone channel, a cord circuit associated therewith and means for observing on the busy telephone channel at any time while the cord is associated therewith, said means including conductors independent of the telephone channel connected to the cord circuit associated with the busy channel.

2. In a service observing system, a service observing position, a telephone operators position, a cord circuit at said operators position comprising answering and calling cord conductors for interconnecting telephone lines, and automatic means for connecting the service observing position to said answering and calling cord conductors for purposes of observation.

3. In a service observing system, a service observing positicn, a telephone operators position, an operators cord circuit at said operators position including answering and calling cord conductors for interconnecting telephone lines, and automatic means initiated at the service observing position for connecting the service observing position to the answering and calling cord conductors.

4. In a service observing system, a means for observing on a busy telephone channel comprising conductors connected to each end of an operators cord circuit independent of the plug terminals of said cord circuit.

5. In a service observing system, an operators cord circuit, a service observing position, and link circuits connecting each end of said cord circuit independently to said position.

6. In a service observing system, telephone lines, a service observing position, an operators position, a plurality of cord circuits for interconnecting said telephone lines at the operators position, a key associated with each cord circuit, a link circuit independent of said telephone lines, means for connecting one end of the link circuit to the service observing position, and means controlled by operation of a key associated with one of the cord circuits for connecting the other end of the link circuit thereto.

'7. In a service observing system, a service observing position, an operators position, a plurality of jacks at the operators position, telephone lines terminating at said jacks, cord circuits at the operators position for interconnecting the telephone lines, means at the service observing position for monitoring on a telephone line connected by a cord circuit and means, also at the observing position, for indicating the condition of the sleeve circuit associated with said connected line.

8. In a telephone exchange system, a service observing position, a plurality of operators positions, a plurality of cord circuits associated with each operators position, a link circuit and an automatic switching mechanism at each end of the link circuit, one switching arrangement serving to connect one end of the link circuit to one of the cord circuits and the other switching arf i rangement serving to connect the other end of the link circuit to the service observing position.

9. In a telephone exchange system, a service observing position, an operators position, a plurality of jacks at the operators position, telephone lines terminating at said jacks, supervisory signals at the operators position for indicating the condition of said telephone lines and signals at the observing position for indicating the condition of said supervisory signals.

l0. In a service observing system, a service observing circuit, an operators position, telephone lines terminating at said operators position, link circuits at said operators position for interconnecting said telephone lines and means for connecting each end of one of said link circuits independently to said service observing circuit for observing on said link circuit.

1l. In a telephone exchange system, a service observing position, an operators position, a plu- Cil rality of jacks at the operators position, telephone lines terminating in said jacks, a plurality of link circuits for interconnecting said telephone lines and means for connecting each end of one of said link circuits independently to the service observing position for observing on said link circuit.

12. In a telephone exchange system, a service observing position, an operators position,. telephone lines terminating at the operators position, a plurality of link circuits at the operators position foi1 interconnecting the telephone lines, means for connecting the service observing position and the operators position, and means at the observing position for indicating which link circuits are being used for interconnecting said lines.

13. In a service observing system, a service observing circuit, a plurality of operators cord circuits for interconnecting telephone lines and means operating without attention on the part of the service observing operator for connecting the observing circuit independent of said telephone lilies in turn to each cord circuit utilized for interconnecting the telephone lines.

14. In a service observing system, telephone lines, a plurality of telephone operators positions, an operators telephone circuit at each of said operators positions, a plurality of cord circuits for interconnecting said telephone lines at each of said operators positions, means for connecting any of said operators telephone circuits to any cord circuit at her position, a plurality of service observing circuits, means for connecting one of said service observing circuits to any one of said operators telephone circuits, other means for disconnecting said service observing circuit from the operators telephone circuit, and automatic switching means, jointly responsive to the operation of said other means and said means for connecting the operators telephone circuit to a cord circuit. for establishing a connection independent of the telephone lines and the operators telephone circuit between the service observing circuit and the cord circuit connected to the operators telephone circuit.

15. In a service observing system, telephone lines, a plurality of telephone operators positions, an operators telephone circuit at each of said operators positions, a plurality of cord circuits for interconnecting said telephone lines at each of said operators positions, means for connecting any of said operators telephone circuits to any cord circuit at her position, a plurality of service observing circuits, means for connecting one of said service observing circuits to any one of said operators telephone circuits, other means for disconnecting said service observing circuit from the operators telephone circuit, and automatic switching means, jointly responsive to the operation of said other means and said means for connecting the operators telephone circuit to a cord circuit, for establishing independent connections between each end of the cord circuit connected to the operators telephone circuit and the service observing circuit.

16. In a service observing system, telephone lines, an operators cord circuit for interconnecting said telephone lines, an operators telephone circuit associated with said cord circuit, a service observing position and a link circuit independent of said telephone lines and of said operators telephone circuit, for connecting said cord circuit and said observing position for observing on said cord circuit.

17. In a service observing system, telephone lines, a service observing circuit, a plurality of operators cord circuits for interconnecting said telephone lines, and means including an automatic selector switch for connecting said service observing circuit independent of said telephone lines with one of said cord circuits for observing thereon.

18. In a service observing system, telephone lines, a plurality of service observing circuits, a plurality of operators cord circuits for interconnecting said telephone lines, and means including an automatic selector switch for connecting one of said service observing circuits independent of said telephone lines with one of said cord circuits for observing thereon.

19. In a service observing system, telephone lines, a service observing position, a plurality of operators cord circuits for interconnecting said telephone lines, an operators telephone circuit associated with said cord circuits, and means controlled at said service observing position for connecting said position independent of said telephone lines and of said operators telephone circuit with one of said operators cord circuits for observing thereon.

20. In a service observing system, telephone lines, a plurality of service observing positions, a plurality of operators cord circuits for interconnecting said telephone lines, and means including a plurality of automatic selector switches for connecting one of said positions independent of said telephone lines with one of said operators' cord circuits for observing thereon.

HENRY E. PHELPS. 

